JP2005196006A - Polarizing plate or retardation plate having acrylic tacky adhesive layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate or retardation plate having an acrylic tacky adhesive layer which does not give rise to foaming even under a high-temperature or high-temperature and high-moisture environment, obviates the occurrence of peeling at the boundary between a glass plate, retardation plate, etc., and an adherend, relaxes the stress concentration caused by elongation and contraction, etc., of a polarizing plate layer, does not generate color unevenness/white voide phenomenon in a liquid crystal element. <P>SOLUTION: The polarizing plate or retardation plate having the acrylic tacky adhesive layer is 30 to 90% in the ratio of the shrinkage rate of the polarizing plate when the polarizing plate is stuck via a tacky adhesive on a glass plate and is left standing for 24 hours at 90°C to the shrinkage rate of the polarizing plate when the polarizing plate is left standing in a free state that the plate is not stuck to the glass plate for 24 hours at 90°C and is 5×10<SP>6</SP>to 5×10<SP>8</SP>Pas in the viscosity coefficient of the tacky adhesive determined from the amount of slippage of the holding power at 90°C when the polarizing plate is stuck via the tacky adhesive. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a polarizing plate or a retardation plate having an adhesive layer, which is used for adhering to an optical component such as a liquid crystal cell of a liquid crystal display device.

A polarizing plate used for a liquid crystal element has a three-layer structure in which both surfaces of a polyvinyl alcohol-based polarizer are sandwiched between triacetyl cellulose-based protective films, but dimensional stability is poor due to the characteristics of these materials. In particular, it is remarkable under heat or wet heat conditions, and the dimensional change due to expansion and contraction of the polarizing plate is large. Therefore, under severe conditions, when the polarizing plate expands and contracts and the followability of the pressure-sensitive adhesive is insufficient, foaming or peeling due to this strain is likely to occur. In addition, since it is impossible to absorb and relieve internal stress caused by dimensional changes over time of the polarizing plate, the distribution of residual stress acting on the polarizing plate becomes non-uniform, particularly stress is concentrated on the periphery of the polarizing plate, As a result, color unevenness and white blurring occur on the surface of the liquid crystal element, such as the peripheral edge of the liquid crystal element being brighter or darker than the center.

In order to solve the above problems, the pressure-sensitive adhesive used for attaching a polarizing plate or a retardation plate to a substrate is usually a small amount of a crosslinking agent added to a high molecular weight polymer to soften the pressure-sensitive adhesive layer. It is made to be strong and resistant to the expansion and contraction of the polarizing plate. Furthermore, by adding a low molecular weight polymer to the pressure-sensitive adhesive, residual stress acting on the polarizing plate is relaxed, and uneven color and white spots are improved.

For example, in Japanese Patent Application Laid-Open No. 10-44293 of Patent Document 1, heat resistance and optical function maintainability are satisfied by defining a 1000% modulus and elongation of an adhesive for optical films having different thermal shrinkage rates at 90 ° C. It states that it can be done. However, controlling the elastic values such as the modulus and elongation of the pressure-sensitive adhesive cannot improve the uneven color and white spots.

Furthermore, in Japanese Patent Application Laid-Open No. 10-279907 of Patent Document 2, an outline “100 parts by weight of a high molecular weight (meth) acrylic copolymer having a weight average molecular weight of 1,000,000 or more and a low weight average molecular weight of 30,000 or less. An invention called “adhesive composition for polarizing plate comprising 20 to 200 parts by weight of a molecular weight (meth) acrylic (co) polymer” and 0.005 to 5 parts by weight of a polyfunctional compound is disclosed. The invention describes that a pressure-sensitive adhesive layer that can follow the dimensional change of the polarizing plate is formed so that the liquid crystal element is less likely to cause uneven color and white spots. However, in the present invention, the amount of polyfunctional compound added is wide, and it is very difficult to adjust the amount of addition in order to make it difficult for color unevenness and white spot phenomenon to occur, and it has a stable pressure-sensitive adhesive layer. It is difficult to manufacture a polarizing plate or a retardation plate.
JP 10-44293 A JP-A-10-279907

The object of the present invention is that foaming does not occur even in a high temperature or high temperature and humidity environment, peeling does not occur at the interface with an adherend such as a glass plate or a retardation plate, and stress concentration caused by expansion and contraction of the polarizing plate layer, etc. An object of the present invention is to provide a polarizing plate or a retardation plate having an acrylic pressure-sensitive adhesive layer that relaxes and does not cause uneven color and white spots in a liquid crystal element.

As a result of intensive studies, the present inventors can adjust the ratio of the contraction rate of the polarizing plate when attached to a glass plate to the contraction rate of the polarizing plate in a free state to be in a specific range. The present invention has been found to be effective in making it difficult to cause foaming and peeling due to dimensional changes under heat and wet heat conditions, and to cause uneven color and white spots.

In other words, the present invention relates to the polarization rate when adhered to a glass plate via an adhesive and left under the same conditions with respect to the contraction rate of the polarizing plate when left at 90 ° C. for 24 hours in a free state where it is not attached to the glass plate. The ratio of the contraction rate of the plate is 30 to 90%, and the viscosity coefficient of the pressure-sensitive adhesive determined from the amount of shift in holding force at 90 ° C. when pasted on the glass plate through the pressure-sensitive adhesive is 5 × 10 ⁶ to It is a polarizing plate or a phase difference plate having an acrylic pressure-sensitive adhesive layer of 5 × 10 ⁸ Pa · s. The acrylic pressure-sensitive adhesive has a weight average molecular weight of 800,000 to 2,000,000 mainly composed of (A) (meth) acrylic acid alkyl ester monomer and carboxyl group and / or hydroxyl group-containing unsaturated monomer. It consists of 100 parts by weight of polymer and 1 to 45 parts by weight of (co) polymer having a weight average molecular weight of 1000 to 300,000 based on (B) (meth) acrylic acid alkyl ester monomer. The pressure-sensitive adhesive is obtained by blending the polymer composition with the crosslinking agent (C) so that the number of theoretical crosslinking points per molecular chain of the copolymer (A) is 2 to 10.

The ratio of the contraction rate of the polarizing plate to 30 to 90% when the polarizing plate is left in a free state at 90 ° C. for 24 hours and is attached to the glass plate via an adhesive and put under the same conditions. By doing so, it is possible to sufficiently absorb and relieve stress due to the contraction of the polarizing plate that occurs under conditions of high temperature and high humidity, and it is possible to prevent the occurrence of foaming, peeling, uneven color, and white spots.

Hereinafter, the configuration of the present invention will be described in detail. Usually, a polarizing plate is manufactured by heating and stretching. For this reason, when the polarizing plate is left in a heat or wet heat environment, it contracts in the stretching direction. In practice, the polarizing plate is used by being attached to a glass plate or a liquid crystal cell via an adhesive. However, if the viscosity coefficient of the adhesive is too large, the polarizing plate can hardly be contracted, and the polarizing plate itself. Distortion remains, resulting in uneven color and white spots. On the other hand, if the viscosity coefficient of the pressure-sensitive adhesive is too small, the polarizing plate shrinks to the extent that it is almost the same as a free state even if it is attached to a glass plate, causing a phenomenon such as foaming or peeling. Therefore, it is necessary for the pressure-sensitive adhesive to move appropriately following the contraction of the polarizing plate.

From the above, the present invention is affixed to the glass plate via an adhesive and left under the same conditions for the shrinkage of the polarizing plate when left at 90 ° C. for 24 hours in a free state where it is not attached to the glass plate. It is necessary that the ratio of the contraction rate of the polarizing plate is 30 to 90%. When the amount is less than 30%, the pressure-sensitive adhesive does not relax when applied to a glass plate or the like, and the polarizing plate hardly contracts. Therefore, stress is applied to the polarizing plate, resulting in uneven color and white spots. When it exceeds 90%, even if affixed to a glass plate or the like, the contraction of the polarizing plate is hardly suppressed, and peeling or blistering occurs. Preferably it is 50 to 90%.

In addition, the ratio of the shrinkage | contraction rate in the state affixed on the glass plate with respect to the shrinkage | contraction rate in the free state of this invention can be calculated | required by the method shown below. The pressure-sensitive adhesive solution was applied to a polyester release film (38 μm) so that the dry coating thickness was 25 μm, dried at 90 ° C. for 60 seconds, transferred onto a polarizing plate, and in an atmosphere of 23 ° C. and 65% RH. For 7 days to obtain a polarizing plate sample. The obtained polarizing plate sample cut into 80 mm × 150 mm so that the absorption axis is 45 ° with respect to the long side of the polarizing plate is used as a test sample. The length (L1) of the diagonal line in the absorption axis direction of the test sample is read and measured with a microscope (manufactured by Nikko Instruments Co., Ltd.). The polarizing plate is sandwiched between two glass plates, left at 90 ° C. for 24 hours, and then the length of the diagonal line (L2) immediately after taking out is measured. The pressure-sensitive adhesive layer surface is covered with a polyester release film (38 μm).
Shrinkage rate in free state (%) = (L1-L2) / L1 × 100 (1)

The above polarizing plate sample is attached to one side of a glass plate by applying a pressure of 5 Kg / cm ² at 50 ° C. via an adhesive and holding for 18 minutes to obtain a test sample. After measuring the length of the diagonal line (L3) in the absorption axis direction of the test sample in the same manner as described above, the test sample is allowed to stand at 90 ° C. for 24 hours, and then the length of the diagonal line (L4) immediately after removal is measured.
Shrinkage rate in a state of being attached to a glass plate (%) = (L3−L4) / L3 × 100 (2)

Therefore, the ratio of the shrinkage rate in the state of being attached to the glass plate with respect to the shrinkage rate in the free state from Equations (1) and (2) can be obtained from Equation (3).
Ratio of shrinkage rate (%) = shrinkage rate in a state of being attached to a glass plate / shrinkage rate in a free state × 100 (3)

Further, the acrylic pressure-sensitive adhesive of the present invention has a viscosity coefficient of 5 × 10 ^{6 to} 5 × 10 ⁸ Pa · determined from the amount of deviation in holding force measurement at 90 ° C. when pasted on a glass plate. It must be s. Within this viscosity coefficient range, it is possible to obtain a polarizing plate that is less susceptible to uneven color, white spots, foaming and peeling.

In addition, the viscosity coefficient of this invention can be calculated | required with the following method. In accordance with the holding power measurement method of JIS Z-0237, a polarizing plate sample obtained in the same manner as the measurement of shrinkage rate was cut into 25 mm × 55 mm so that the absorption axis was 90 ° with respect to the long side of the polarizing plate. Then, a pressure of 5 Kg / cm ² was applied to the glass plate at 50 ° C. so that the adhesion area would be 25 mm × 10 mm, and the test sample was held for 18 minutes and adhered. The test sample is suspended in a 90 ° C. atmosphere at a load of 9.8 N, and the amount of deviation after 1 hour is measured. The viscosity coefficient of the adhesive is calculated from this deviation amount.
Shear stress (N / m ² ) = load / bonding area = 9.8 N / 0.025 m × 0.01 m
Deviation speed (1 / s) = deviation amount / time / thickness = deviation amount (m) / 3600 seconds / 0.000025 m
Viscosity coefficient (Pa · s) = shear stress / shear rate

The copolymer (A) constituting the acrylic pressure-sensitive adhesive layer of the present invention is a pressure-sensitive adhesive composition containing (meth) acrylic acid alkyl ester monomer and carboxyl group and / or hydroxyl group-containing monomer as main components. It is. Specifically, the (meth) acrylic acid alkyl ester monomer used is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, 2- Examples include ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate, and the like. At least one selected from these groups can be used.

The carboxyl group and / or hydroxyl group-containing monomer used in the copolymer (A) is specifically a (meth) acrylic acid, itaconic acid, maleic acid, maleic anhydride, Examples thereof include fumaric acid and fumaric anhydride, and at least one selected from these groups can be used. (Meth) acrylic acid is preferred. Specific examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, caprolactone-modified (meth) acrylate, polyethylene glycol (meta ) Acrylate, polypropylene glycol (meth) acrylate, and the like, and at least one selected from these groups can be used. The carboxyl group-containing monomer and the hydroxyl group-containing monomer can be used alone or in combination. The usage-amount of a carboxyl group and / or a hydroxyl-containing monomer is 0.01 to 10 weight% with respect to the monomer whole quantity. If the amount used is less than 0.01% by weight, the degree of cross-linking is small and deviation at normal temperature is likely to occur, and if the amount used exceeds 10% by weight, the stress due to expansion and contraction of the polarizing plate layer Concentration cannot be absorbed or relaxed sufficiently. Preferably it is 0.1-7.0 weight%. More preferably, it is 0.5 to 5% by weight.

It is necessary that the copolymer (A) constituting the acrylic pressure-sensitive adhesive layer of the present invention has a weight average molecular weight of 800,000 to 2,000,000. When the weight average molecular weight is less than 800,000, even if a crosslinking agent is used, the cohesive force is insufficient and foaming or peeling off from the polarizing plate is likely to occur. When the weight average molecular weight exceeds 2 million, the stress concentration resulting from the expansion and contraction of the polarizing plate layer cannot be sufficiently absorbed and relaxed, the coating viscosity becomes too high, and the workability is inferior.

The (co) polymer (B) mainly composed of (meth) acrylic acid alkyl ester constituting the acrylic pressure-sensitive adhesive layer of the present invention has color irregularities and white spots caused by minute distortion caused by changes in the dimensions of the polarizing plate. It is an indispensable component for preventing foaming, peeling and the like accompanying dimensional changes under high temperature and high humidity conditions without deteriorating the phenomenon. The effect of the (co) polymer (B) is that the weight average molecular weight is small, so it enters between the copolymers (A) forming a network structure by the crosslinking agent, and plasticizes the copolymer (A). It is thought to have the effect of improving the elasticity and flexibility, and preventing uneven color and white spots.

The (meth) acrylic acid alkyl ester monomer used in the (co) polymer (B) constituting the acrylic pressure-sensitive adhesive layer of the present invention is the (meth) acrylic acid alkyl ester used in the copolymer (A). Monomers can be used. Preferably, it does not have a functional group-containing monomer.

The weight average molecular weight of the (co) polymer (B) constituting the acrylic pressure-sensitive adhesive layer of the present invention needs to be 1000 to 300,000. When the weight average molecular weight is less than 1000, the cohesive force is reduced, which causes foaming and peeling. When it exceeds 300,000, the flexibility is lowered, and it is difficult to prevent uneven color and white spots.

The usage-amount of the (co) polymer (B) which comprises the acrylic adhesive layer of this invention needs 1-45 weight part with respect to 100 weight part of copolymers (A). When the amount used is less than 1 part by weight, it is difficult to sufficiently absorb and relax the stress concentration caused by the expansion and contraction of the polarizing plate layer. If the amount used exceeds 45 parts by weight, the cohesive force is reduced, causing foaming and peeling. Preferably it is 5-40 weight part.

The weight average molecular weight is a molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) (model: LC-10ADVP, manufactured by Shimadzu Corporation, column: KF-G, KF-806M).

The crosslinking agent (C) to be added to the acrylic pressure-sensitive adhesive of the present invention can use a compound that reacts with a carboxyl group and / or a hydroxyl group, and is necessary for increasing the cohesive strength of the pressure-sensitive adhesive. As a crosslinking agent that can be used, a glycidyl compound having at least two glycidyl groups in one molecule, an isocyanate compound having two or more isocyanate groups in one molecule, and an aziridine compound having at least two aziridinyl groups in one molecule An oxazoline compound having an oxazoline group in one molecule, a metal chelate compound, a butylated melamine compound, or the like can be used. Preferred are glycidyl compounds, isocyanate compounds and aziridine compounds.

The amount of use must be blended so that the number of theoretical crosslinking points per molecular chain of the copolymer (A) is 2 to 10. When the number of theoretical crosslinking points is less than 2, the cohesive force of the pressure-sensitive adhesive is low, which causes foaming or peeling. When the number of theoretical crosslinking points exceeds 10, it is difficult to sufficiently absorb and relax the stress concentration caused by the expansion and contraction of the polarizing plate layer.

In addition, the calculation method of the number of theoretical bridge | crosslinking points can be calculated | required from the following formula.
Number of moles of polymer of copolymer (A) = weight of copolymer (A) / number of moles of reactive group in weight average molecular weight crosslinking agent of copolymer (A) = weight of blended crosslinking agent × unit weight The number of reactive groups of the crosslinking agent per theoretical number of crosslinking points = number of moles of reactive groups of the crosslinking agent / number of moles of polymer

The glycidyl compound that can be used as the crosslinking agent used in the acrylic pressure-sensitive adhesive of the present invention is a glycidyl compound having at least two glycidyl groups in one molecule. Specifically, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether , Tetraglycidylxylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, etc. A glycidyl compound is mentioned, At least 1 sort (s) chosen from these groups can be used.

The isocyanate compound that can be used as the crosslinking agent used in the acrylic pressure-sensitive adhesive of the present invention is an isocyanate compound having at least two isocyanate groups in one molecule. Specific examples include tolylene diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and prepolymers modified from these, and at least one selected from these groups can be used. A non-yellowing type of hexamethylene diisocyanate or isophorone diisocyanate is preferable.

The aziridine compound that can be used as a crosslinking agent for use in the acrylic pressure-sensitive adhesive of the present invention is an aziridine compound having at least two aziridinyl groups in one molecule. Specifically, 1,1 ′-(methylene-di-p-phenylene) bis-3,3-aziridylurea, 1,1 ′-(hexamethylene) bis-3,3-aziridylurea, ethylenebis (2-aziridinyl) Lupropionate), tris (1-aziridinyl) phosphine oxide, 2,4,6-triaziridinyl-1,3,5-triazine, trimethylolpropanthris (2-aziridinylpropionate), etc. Is mentioned. At least one selected from these groups can be used.

In the acrylic pressure-sensitive adhesive of the present invention, a silane compound containing a mercaptoalkyl group and an alkoxy group simultaneously in the molecule can be used. By using a silane compound containing a mercaptoalkyl group and an alkoxy group in the molecule at the same time, the adhesion to the glass substrate surface as the adherend can be further improved. Specific examples of the silane compound containing a mercaptoalkyl group and an alkoxy group in the molecule used in the present invention include γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, mercaptobutyltrimethoxysilane, γ -Mercaptopropylmethyldimethoxysilane, mercapto group-containing alkoxysilane oligomer and the like. At least one selected from these groups can be used.

The amount of the silane compound containing a mercaptoalkyl group and an alkoxy group simultaneously in the molecule used in the acrylic pressure-sensitive adhesive of the present invention is 0.01 to 2 parts by weight with respect to 100 parts by weight of the copolymer (A). is there. When the amount used is less than 0.01 parts by weight, the effect of enhancing the adhesion to the glass substrate surface, which is the adherend, is small, and when it exceeds 2 parts by weight, the pressure-sensitive adhesive layer is peeled off.

The copolymer (A) constituting the acrylic pressure-sensitive adhesive layer of the present invention can be usually produced by bulk polymerization or solution polymerization. Solution polymerization is preferred. The solvent used is an organic solvent used for a solution polymerization reaction such as ethyl acetate, toluene, n-hexane, acetone, methyl ethyl ketone. The polymerization initiator used in the polymerization may be a polymer azo polymerization initiator alone or the polymerization initiator and other azobisisobutyronitrile, azobisvaleronitrile, etc. for the polymerization reaction of the copolymer (A). An azobis compound can be used in combination.

The (co) polymer (B) constituting the acrylic pressure-sensitive adhesive layer of the present invention can be produced by the same method, bulk polymerization, solution polymerization, living polymerization and the like as the copolymer (A). For example, in radical polymerization in a solvent, the amount of polymerization initiator used is about 5 to 30 times the amount used when polymerizing a normal pressure-sensitive adhesive. Further, mercaptans such as lauryl mercaptan, α-methylstyrene dimer Etc. are used. Further, the target (co) polymer (B) can be obtained by fractional precipitation using a solvent such as heptane in order to narrow the molecular weight dispersion. A low molecular weight polymer can also be obtained by a living polymerization method. Furthermore, a known low molecular weight type solventless acrylic polymer obtained by a bulk polymerization method can also be used.

You may mix | blend various things as needed for the purpose of adjusting the adhesiveness of the copolymer (A) which comprises the acrylic adhesive layer of this invention. Specific examples used for blending include terpene, terpene-phenol, coumarone indene, styrene, rosin, xylene, phenol, petroleum and other tackifying resins, antioxidants, UV absorbers , Fillers, pigments and the like.

The polarizing plate or retardation plate of the present invention can be produced by the following production method. The acrylic adhesive of the present invention is applied to a polyester release film of 20 to 50 μm with a commonly used coating apparatus such as a roll coating apparatus so that the dry coating thickness is 10 to 50 μm, preferably 15 to 40 μm. Then, it is dried at 80 to 120 ° C. for 30 to 120 seconds, transferred onto a polarizing plate, and cured for 3 to 7 days or more in an atmosphere at room temperature to 40 ° C., whereby the polarized light having the acrylic pressure-sensitive adhesive layer of the present invention. A plate or a phase difference plate can be obtained.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not restrict | limited by this. In the examples and comparative examples, “part” or “%” means “part by weight” or “% by weight” unless otherwise specified.

Production Example 1 (Copolymer A-1)
After nitrogen gas is sealed in a reactor equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen introduction tube, 70 parts of ethyl acetate, 15 parts of acetone, 99 parts of butyl acrylate, 1 part of acrylic acid, azo polymerization 0.1 part of initiator 2,2′-azobisisobutyronitrile (trade name V-60, Wako Pure Chemical Industries, Ltd.) is charged. The reaction is carried out for 8 hours at the reflux temperature of the solvent in a nitrogen gas stream with stirring. After completion of the reaction, 315 parts of toluene is added and cooled to room temperature. A copolymer A-1 having a viscosity of 7,000 mPa · s, a solid content of 20.0%, and a weight average molecular weight of 1.35 million was obtained.

Production Example 2 (Copolymer A-2)
Manufacture example 2 obtained copolymer A-2 like manufacture example 1 except changing the kind and quantity of a monomer as shown in Table 1. The analytical values are shown in Table 1.

Production Example 3 (Copolymer B-1)
After nitrogen gas was sealed in the same reactor as in Production Example 1, 60 parts of ethyl acetate, 10 parts of acetone, 100 parts of butyl acrylate, 0.2 part of lauryl mercaptan, azo-based polymerization initiator 2,2′-azobisiso 0.1 part of butyronitrile (trade name V-60, Wako Pure Chemical Industries, Ltd.) is charged. The reaction was carried out for 4.5 hours at the reflux temperature of the solvent in a nitrogen gas stream while stirring. After completion of the reaction, 80 parts of toluene is added and cooled to room temperature. A copolymer B-1 having a viscosity of 300 mPa · s, a solid content of 40.0%, and a weight average molecular weight of 200,000 was obtained.

In Table 1, the types of monomers are indicated by the following abbreviations.
Monomer BA: Butyl acrylate MA: Methyl acrylate AAc: Acrylic acid 2HEMA: 2 Hydroxyethyl methacrylate

The weight average molecular weight in Table 1 is a molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) (model: LC-10ADVP, manufactured by Shimadzu Corporation, column: KF-G, KF-806M).

The (co) polymer (B) used in the acrylic pressure-sensitive adhesive layer of the laminate of the present invention is a low molecular weight type of a commercially available product (trade name Alfon, manufactured by Toagosei Co., Ltd.) as shown in Table 2 below. Solvent acrylic polymers can also be used.

The solid content of the copolymer A-1 solution obtained in Production Example 1 was mixed with 100 parts by weight of the solid content of the polymer B-1 solution obtained in Production Example 3, so that the solid content was 40 parts by weight. Add 0.08 parts by weight of solid biuret type of hexamethylene diisocyanate (trade name Duranate 24A-100, manufactured by Asahi Kasei Kogyo Co., Ltd.) as a crosslinking agent and stir well. The prepared adhesive solution is applied to a polyester release film (38 μm) so that the dry coating thickness is 25 μm, dried at 90 ° C. for 60 seconds, and transferred onto a polarizing plate (general polarizing plate, thickness 100 μm). Then, it was cured in an atmosphere of 23 ° C. and 65% RH for 7 days to obtain a polarizing plate sample. The obtained polarizing plate sample was cut into 80 mm × 150 mm so that the absorption axis was 45 ° with respect to the long side of the polarizing plate, and a pressure of 5 kg / cm ² was applied to one side of the glass plate at 50 ° C. As a result of leaving the test samples held for 90 minutes in an atmosphere of 90 ° C., 60 ° C. and 90% RH for 500 hours and examining the occurrence of foaming and peeling, both were good. The obtained polarizing plate sample was placed on both surfaces of the glass plate so that the absorption axis was perpendicular, a pressure of 5 Kg / cm ² was applied at 50 ° C., and the test sample was held for 18 minutes and bonded to 90 ° C. As a result of examining the state of occurrence of uneven color and white spots, it was good. The shrinkage after leaving only the polarizing plate at 90 ° C. for 24 hours was 0.99%, and the shrinkage after sticking to a glass plate with an adhesive and leaving it at 90 ° C. for 24 hours was 0.79%. It was. The ratio of the shrinkage rate when adhered to the glass plate relative to the shrinkage rate in the free state was 80%. Moreover, as a result of sticking to a glass plate and measuring the holding force at 90 ° C., the deviation after 1 hour was 0.1 mm, and the viscosity coefficient of the adhesive was 3.5 × 10 ⁷ Pa · s. Furthermore, the number of theoretical crosslinking points was 6 / one polymer. The heat resistance, heat-and-moisture resistance, color unevenness and white spot test were all good. The results are shown in Table 3.

In Example 2, the amounts of copolymer A-1, polymer B-1 and crosslinking agent were blended as shown in Table 3, and γ-mercaptopropyltrimethoxysilane (Nihon Unicar Co., Ltd.), which is a silane compound, was added. Manufactured, trade name: AZ-6129) Except for adding 0.3 parts by weight, it was adjusted and tested in the same manner as in Example 1. All the results were good. The results are shown in Table 3.

Example 3 is the same as Example 2 except that Alfon UP-1000 is blended as shown in Table 3 instead of the polymer B-1 of Example 2, and the polarizing plate is changed to a general polarizing plate (thickness: 180 μm). The test was carried out in the same manner as in 1. All the results were good. The results are shown in Table 3.

In Example 4, as shown in Table 3, the copolymer (A) is A-2, the (co) polymer (B) is Alfone UP-1000, and the crosslinking agent (C) is N, N, N ′, N Except for using '-tetraglycidyl m-xylenediamine (trade name Tetrad X, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and changing the polarizing plate to a wide viewing angle polarizing plate (thickness 180 μm), it is exactly the same as Example 1. Similarly adjusted and tested. All the results were good. The results are shown in Table 3.

Comparative Example 1
Comparative Example 1 is an example in which the crosslinking agent of Example 1 is increased. The number of theoretical cross-linking points increased to 11.3, and the shrinkage rate was as low as 20%, resulting in uneven color and white spots. Furthermore, the amount of deviation became smaller and the viscosity coefficient was larger. The results are shown in Table 4.

Comparative Example 2
Comparative Example 2 is an example in which the crosslinking agent of Example 2 was reduced. Since the number of theoretical cross-linking points was as small as 1.5 and the shrinkage ratio was as large as 96%, foaming was observed with heat resistance and moist heat resistance, and the deviation amount was large and the viscosity coefficient was small. The results are shown in Table 4.

Comparative Example 3
Comparative Example 3 is an example in which the amount of the cross-linking agent is increased except for copolymer A alone and low-molecular weight copolymer B. Since the number of theoretical crosslinking points was as large as 15.1 and the rate of shrinkage was as small as 10%, color unevenness and white spotting occurred, and the amount of deviation was small and the viscosity coefficient was large. The polarizing plate used was a general polarizing plate (thickness 180 μm). The results are shown in Table 4.

The types of polarizing plates in Tables 3 and 4 are as follows.
A: General polarizing plate, thickness 100 μm
B: General polarizing plate, thickness 180 μm
C: Wide viewing angle polarizing plate, thickness 180 μm

In Tables 3 and 4, the crosslinking agent and the silane compound are indicated by the following abbreviations.
Crosslinking agent C-1: Asahi Kasei Co., Ltd. product name Duranate 24A-100
Number of functional groups: 3
NCO content (wt%): 23.5
NCO content (g / g): 0.235
NCO content (eq / g): 0.0056 (the number of reactive groups of the crosslinking agent per unit weight)
C-2: Mitsubishi Gas Chemical Co., Ltd. trade name Tetrad X
Number of functional groups: 4
Epoxy equivalent: 90
Epoxy content (wt%)
: 47.8
Epoxy content (g / g): 0.478
Epoxy content (eq / g): 0.0111 (the number of reactive groups of the crosslinking agent per unit weight)
Silane compound: Nippon Unicar Co., Ltd. product name AZ-6129

Test method
1. Shrinkage rate The pressure-sensitive adhesive solution of the present invention was applied to a polyester release film (38 μm) so that the dry film thickness was 25 μm, dried at 90 ° C. for 60 seconds, transferred onto a polarizing plate, and 23 ° C. A polarizing plate sample was obtained by curing for 7 days in an atmosphere of 65% RH. The obtained polarizing plate sample is cut into 80 mm × 150 mm so that the absorption axis is 45 ° with respect to the long side of the polarizing plate. The length (L1) of the diagonal line in the absorption axis direction of the sample was read and measured with a microscope (manufactured by Nippon Kogyo Co., Ltd.). The polarizing plate is sandwiched between two glass plates, left at 90 ° C. for 24 hours, and then the length of the diagonal line (L2) immediately after taking out is measured.
Shrinkage rate in free state (%) = (L1−L2) / L1 × 100 (1)
The sample was made into the test sample which applied the pressure of 5 Kg / cm < ² > at 50 degreeC to the single side | surface of the glass plate, hold | maintained for 18 minutes, and bonded together. After measuring the length of the diagonal line (L3) in the absorption axis direction of the test sample, the test sample is allowed to stand at 90 ° C. for 24 hours, and then the length of the diagonal line (L4) immediately after removal is measured.
Shrinkage ratio (%) = (L3−L4) / L3 × 100 (2) when attached to a glass plate
The ratio of the shrinkage rate in the state of being attached to the glass plate to the shrinkage rate in the free state from the equations (1) and (2) is obtained from the equation (3).
Ratio of shrinkage rate (%) = shrinkage rate in a state of being attached to a glass plate / shrinkage rate in a free state × 100 (3)

2. A polarizing plate sample obtained in the same manner as in the measurement of the shrinkage rate according to the holding power measurement method of viscosity coefficient JIS Z-0237 is 25 mm × so that the absorption axis is 90 ° with respect to the long side of the polarizing plate. The test sample was cut to 55 mm, bonded to a glass plate so that the bonding area was 25 mm × 10 mm, and a pressure of 5 kg / cm ² was applied at 50 ° C. and held for 18 minutes. Suspend a load of 9.8 N and measure the amount of deviation after 1 hour. The viscosity coefficient of the adhesive is calculated from this deviation amount.
Shear stress (N / m ² ) = load / bonding area = 9.8 N / 0.025 m × 0.01 m
Deviation speed (1 / s) = deviation amount / time / thickness = deviation amount (m) / 3600 seconds / 0.000025 m
Viscosity coefficient (Pa · s) = shear stress / shear rate

3. Heat resistance and moist heat resistance A polarizing plate sample obtained in the same manner as in the measurement of the shrinkage rate was cut into 80 mm × 150 mm so that the absorption axis was 45 ° with respect to the long side of the polarizing plate. A test sample was prepared by applying a pressure of 5 kg / cm ² at 50 ° C. to the sample and holding it for 18 minutes. For heat resistance, the test sample obtained as described above is left in a constant temperature bath at 90 ° C. for 500 hours, returned to room temperature, and observed for foaming and peeling. For heat and moisture resistance, the test sample obtained as described above is left in a constant temperature and humidity chamber at 60 ° C. and 95% RH for 500 hours, returned to room temperature, and observed for the occurrence of foaming and peeling.
○: No change in appearance such as foaming or peeling.
Δ: Little change in appearance such as foaming and peeling.
X: Appearance changes such as foaming and peeling are considerable.

4). Color unevenness / white spot test A polarizing plate sample obtained in the same manner as in the above measurement of the shrinkage rate was placed on both surfaces of a glass plate so that the absorption axis was perpendicular, and a pressure of 5 kg / cm ² at 50 ° C. The test sample, which was held for 18 minutes and pasted, was observed in a 90 ° C. atmosphere for 500 hours, and then observed for uneven color and white spots.
○: Uneven color and white spots are not recognized at all.
Δ: Color unevenness and white spots are slightly noticeable.
X: Color unevenness and white spots are large.

It can be used for the production of polarizing plates and retardation plates that do not cause foaming or peeling due to cross-linking distortion or residual stress of the polarizing plates or retardation plates, and uneven color or white spots.

Claims (2)

Compared to the shrinkage rate of the polarizing plate when left at 90 ° C. for 24 hours in a free state where it is not attached to the glass plate, the shrinkage rate of the polarizing plate when attached to the glass plate via an adhesive and left under the same conditions The viscosity coefficient of the pressure-sensitive adhesive is 5 × 10 ^{6 to} 5 × 10 ⁸ Pa determined from the amount of shift in holding force at 90 ° C. when the ratio is 30 to 90% and attached to the glass plate via the pressure-sensitive adhesive. A polarizing plate or a retardation plate having an acrylic adhesive layer that is s. (A) (meth) acrylic acid alkyl ester monomer, and 100 parts by weight of a copolymer having a weight average molecular weight of 800,000 to 2,000,000 having a carboxyl group and / or a hydroxyl group-containing unsaturated monomer as main components (B) a (co) polymer composition comprising 1 to 45 parts by weight of a (co) polymer having a weight average molecular weight of 1000 to 300,000 having a (meth) acrylic acid alkyl ester monomer as a main component, 2. The polarized light according to claim 1, further comprising an acrylic pressure-sensitive adhesive layer formed by blending a crosslinking agent (C) so that the number of theoretical crosslinking points per molecular chain of the copolymer (A) is 2 to 10. 3. Plate or phase difference plate.